1. Unix common interview questions, $$, $#, $*, $?

[dtech-team]

Few Interview questions:

1. What does these indicate in UNIX?

$$
$?
$*
$#
$1

[dtech-team]

Really forgot this one:

$?  - shows the status of the previsously executed command. (Success - 0, fail >0)

$* - gives the list of all input parameters to a shell script

$# -gives the total number of input parameters to a shell script
 
$1 - gives the value of first input, $2 gives second input and so on...

$$ -- Process number of current shell

[devtakh]

To add on the list

$0 - name of the executed command/script
$@ - same as $* except when enclosed in double quotes
$! -pid of the last backgnd process.

[dtech-team]

Hi Dev, Thanks yaar..

Our Unix professor is back !!! 

[dtech-team]

More: http://baishui.info/orelly/unix/unixnut/ch05_03.htm